The present invention relates to the field of commercial building construction, and in particular to buildings with concrete floors supported on steel joists, and preferably where the floors are composite steel and concrete structures.
When using steel supported concrete floors in a building, the conventional practice is to erect the steel joists on support walls and to pour each concrete floor once the steel joists and floor pan have been placed. Further vertical walls for the next story of the building are then erected, and joists are supported on the walls. The construction proceeds one floor at a time with a separate concrete pour occurring for each floor, requiring numerous returns of the concrete pouring crew during construction. Further the labor used to erect walls is not required when the concrete is being set in place.
It would be highly desirable to be able to form up the entire building in an uninterrupted manner at one time and pour the concrete floors following the erection of the structure in an independent manner The alternate work of framing and concreting crews would be avoided, and significant cost savings in the construction would be achieved. In order to achieve this significant improvement, it has been found that changes are required in both the structural design of the building, and that these changes improve both the speed and convenience of construction, and the structural strength of the building both before and after the pouring of the concrete floors.
In civil engineering ring beams are used as continuous tension members surrounding the perimeter domes, hemispheres, and like structures which carry compression forces from loads supported by them and tension forces caused by the load seeking to spread the ring. The ring beam is designed to resist both forces. Ring beams need not be circular, but may be conformed to the shape of the structure in which it is incorporated. It is a compression/tension member to resist these forces in the structure.
For the use of structural members commonly known as joists, in conjunction with metal stud, wood stud or prefabricated wall panels, it is necessary to provide an effective means to distribute the resulting dead and live point loads resulting from these members. For the fastest speed of construction, it is of particular importance to have a joist-support-system that will spread loads along the wall concentrically, while at the same time allowing the erection of multiple floors without the need to have concrete in place. Presently the construction industry does not have an efficient system to enable the facilitation of all of the above criteria, via a pre-designed integrated-modular-component-system. In today""s construction industry, it is overly complicated to satisfy all of the above criteria, and requires the use of many project-specific details.
The present invention has been developed to provide a modular approach to satisfy all of the above criteria. The system allows the planner of a multi-storey building project to remove concrete from the critical path of the structure and envelope completion. The system of the present invention accommodates various floor depths, conforms to alternative stud depths and, acts as a compression/tension member for a building during and after construction. The invention relies upon the use of cold-formed metal that is shaped to provide a ring beam which will accommodate the various criteria. Notably, the system spreads the concentrated load to many adjacent studs to limit the direct load on one stud along the load bearing wall. After 2 or 3 levels in a multi-storey project are formed, the concentrated loads are uniformly distributed over all the stud walls.
The ring beam structure is formed of a hat section that is positioned with the open side facing in, atop each level of the perimeter wall of the building at each floor location, which is supported by the wall, and provides a seat supporting the floor joists, and in turn supports the next level of the perimeter wall. Stabilizer struts are positioned at required intervals to stabilize the ring beam section during erection of the building frame and prior to concreting. In addition to serving as a structural member in the building frame the ring beam also acts as a passive pour stop to prevent the escape of concrete when floors are being poured. The ring beam also provides a continuous tension/compression ring at the perimeter of the floor system when tension/compression struts are installed at the splices of the ring beam. The basic shapes developed for supporting joists before and after concreting are a ring beam formed of a hat section with variable dimensioning capability, a stabilizer strut which can be fastened to the flanges of the hat section, and tension/compression struts which are similarly fastened to the flanges of adjacent hat sections, as will be detailed below.